1. Field of the Invention
Apparatuses consistent with the present invention relate to a liquid crystal display (LCD) apparatus, and more particularly, to an LCD apparatus which comprises a backlight array on which a plurality of light emitting devices illuminating an LCD panel with a plurality of colors is arranged to have a predetermined pattern, and controls the backlight array to adjust a white balance.
2. Description of the Related Art
An LCD apparatus uses a liquid crystal cell of which an inherent molecular arrangement is rearranged when a voltage is applied thereto such that the molecular rearrangement causes optical properties such as birefringence, line light, dichroism, light scattering, etc., thereby modulating light and displaying a picture.
As compared with other display apparatus such as a plasma display panel (PDP), a field emission display (FED), etc., the LCD apparatus cannot emit light itself and, instead, adjusts the light passing through an LCD panel, so that a separate light source is needed.
Therefore, the LCD apparatus comprises a backlight unit as well as the LCD panel so as to illuminate the LCD panel in a back thereof. Generally, the backlight unit comprises a lamp used as a light source; a light guided panel changing light emitted from the lamp into a surface light source and enhancing photo-efficiency and brightness; a prism sheet, and an optical sheet such as a polarizer. Additionally, an inverter controls light intensity of the lamp, thereby adjusting the brightness of a picture displayed on the LCD panel.
The lamp used as the light source is generally a cathode fluorescent lamp such as a cold cathode fluorescent lamp (CCFL), a hot cathode fluorescent lamp (HCFL), etc., which emits white light.
On the other hand, a phase alternate line (PAL) standard, a sequential couleur a memoire (SECAM) standard, or a national television system committee (NTSC) standard are currently used as a television broadcast standard. As such, a conventional LCD apparatus is designed to support only one among the foregoing broadcast standards, or support two or more among the foregoing broadcast standards. The conventional LCD apparatus adjusts a white balance according to each broadcast standard by applying a predetermined signal-processing algorithm to a video signal according to each broadcast standard.
For example, as a white balance adjusting method according to each broadcast standard, a maximum brightness is calculated by changing contrast gains of a red (R) signal, a green (G) signal and a blue (B) signal contained in the video signal, respectively. Therefore the R, G, B signals are adjusted in contrast at the maximum brightness, thereby adjusting the white balance.
Then, the white balance is adjusted by adjusting the brightness of the R, G, B signals at a minimum brightness of the video signal. Thereafter, a gamma value is set on the basis of the maximum and minimum values of the adjusted G signal and is identically set as to the R and B signals. Then, with regard to gradation of an adjustable range, the set gamma value of the G signal value is fixed and the set gamma values of the R and B signals are varied to thereby adjust the white balance.
However, in the conventional white balance adjusting method based on the cutoff value and the gamma correction of the R, G, B signals, the white balance is adjusted by changing the contrast and the brightness of the video signal, so that a contrast ratio of the conventional LCD apparatus is lowered. Further, the white balance is adjusted on the basis of the maximum and minimum brightness of the respective R, G, B signals, so that there is a loss in a representable brightness level, i.e., brightness.